When any drainage project operating under the provisions of this chapter shall have bonds outstanding, either due or to become due, and when it shall seem to the board of viewers having jurisdiction over such drainage project that it is to the best interest of such drainage project to refund such outstanding bonds in whole or in part, such board of viewers is hereby authorized to refund all or part of such outstanding bonds by the issuance of the negotiable refunding bonds of such project.
Va. Code § 21-412